1. Field of the Invention
This invention relates to diagnostic method and apparatus based upon a functional polymorphism in the promoter of a gene encoding macrophage migration inhibitory factor (MIF). More specifically, this invention relates to a method for diagnosis of predisposition to certain disease states, by screening for the presence of this promoter polymorphism. The invention also relates to apparatus for screening for the polymorphism, MIF genes containing the polymorphism and to a probe therefor.
2. Background of the Technology
A number of experimental studies have led to the concept that macrophage migration inhibitory factor (MIF) functions as a physiological counter-regulator of glucocorticoid action within the immune system. In this role, MIF's position within the cytokine cascade is to act in concert with endogenous glucocorticoids to control the set point and the magnitude of the inflammatory response (1). MIF also has several direct, pro-inflammatory roles in inflammatory diseases such as rheumatoid arthritis (2), sepsis (3, 4), acute respiratory distress syndrome (5), and glomerulonephritis (6).
MIF was originally described over 30 years ago as a T-lymphocyte-derived factor that inhibited the migration of peritoneal macrophages (7), but it is now known that several other cell types, including macrophages themselves, are important sources of MIF (8), MIF levels are elevated in the serum and synovial fluid of patients with rheumatoid arthritis (2, 9), and within the synovial joint MIF immunostaining can be localized to the synovial lining CD14+ macrophages and fibroblast-like synoviocytes (2). Upon release MIF is directly pro-inflammatory by activating or promoting cytokine expression (TNFα (8, 10), IL-1β, IL-2 (11), IL-6 (8,12), IL-8 (13) and IFNγ (11, 14)), nitric oxide release (15), matrix metalloproteinase (MMP) expression (16, 17), and induction of the cyclooxygenase-2 (Cox-2) pathway (18). MIF's capacity to induce to sustained activation of the p44/p42 (ERK-1/2) MAP kinase pathway (18) and to inhibit p53-dependent apoptosis (19, 20) also suggest that this mediator may play a key role in initiation of rheumatoid pannus.
U.S. Pat. No. 6,030,615 to Bucala. et al. discloses a combination method for treating diseases caused by cytokine-mediated toxicity, comprising administering an effective amount of (a) an MIF inhibitor, such as an antibody that binds to an MIF polypeptide, wherein the MIF polypeptide has a molecular weight of about 12.5 kDa in combination with (b) anti-TNFα, anti-IL1, anti-IFN-γ, IL-1RA, a steroid, a glucocorticoid, or IL-10.
The concept that polymorphisms in immune response genes contribute to the pathogenesis of certain human autoimmune/inflammatory diseases has received increasing interest over the last several years. At present, very few gene polymorphisms have been shown to be functionally significant and to be of prognostic value in specific disease states. Previously defined examples include polymorphisms in TNFα and IL-1ra that have been shown to have certain prognostic significance in malaria and ischaemic heart disease respectively (24,25). Similarly, a number, of polymorphisms in TNFα and IL-β have been reported to be associated with rheumatoid arthritis severity (26-28).